A disclosed tool changer (for example, Patent Literature 1) that is applied to an industrial robot as one of various instruments includes a male member attached to the robot and a female member attached to a tool. The tool changer is provided with, depending on its usage, power supplying modules for transmitting electrical power or an electric signal from the robot to the tool through a cable. The power supplying modules are attached to the male member and the female member, respectively, and include contact portions that are electrically connected to each other when the male member and the female member are coupled to each other, and connector units to which external cables are connected.